US3396964A - Sheet feeding apparatus - Google Patents

Description

3, 1968 H. FENGLER ET AL 3396,964

SHEET FEEDING APPARATUS 3 Sheets5heet 1 Filed Sept. 20, 1966 INVENTOR. HARALD FENGLER HELMUT SCHAUSBERGER FRANZ KOCOUREK fl 4(! f rflflr Aug. 13, 1968 Filed Sept. 20, 1966 H. FENGLER ET AL SHEET FEEDING APPARATUS Sheets-Sheet 5 INVENTOR.

HARALD FENGLER HELMUT SCHAUSBERGER FRANZ KOCOUREK United States Patent O 3396964 SHEET FEEDING APPARATUS Harald Fengler, Helmut Schausberger, and Franz Kocourek, Munich, Germany, assignors (o Agfa- Gevaert Aktiengesellschaft, Leverkusen, Germany Filed Sept. 20, 1966, Sex. N0. 580,763 Claims priority, applicxtigg ermany, Sept. 21, 1965,

34 Claims. Cl. 271s ABSTRACT OF THE DISCLOSURE The present invention relates to apparatus for feeding sheets, particularly to apparatus for feeding sheets of exposed film to developing units. Still more particularly, the invention relates to improvements in apparatus for feeding sheets by means of suction cups or analogous suctionoperated transfer devices.

An important object of the invention is to provide an apparatus which can transfer sheets from a pile in the Same sequence in which the sheets are stacked to form the pile.

Another object of the invention is to provide an apparatus which can maintain a pile of sheets in such position that the individual sheets are not subjected to excessive pressure which could result in simultaneous transfer of two or more sheets or in undesirable shifting of remaining sheets during transfer of successive foremost sheets for further processing.

A further object of the invention is to provide a sheet feeding apparatus which can transfer sheets out of turn if such sheets are being adrnitted frorn a separate source.

An additional object of the invention is to provide an apparatus of the above outlined characteristics with a simple but reliable arrangement which can automatically interrupt the feed of sheets if the suction-operated device transfers from the pile two or more sheets at a time or if such device happens to withdraw an unsatisfactory sheet, particularly a sheet of excessive thickness.

A concomitant object of the invention is to provide an apparatus which can transfer successive sheets at desired intervals so that such sheets cannot interfere with each other.

Still another object of the invention is to provide an apparatus wherein the sheets are automatically oriented to assume an optimum position prior to undergoing further treatment.

A further object of the invention is to provide a sheet feeding apparatus which can receive a fresh supply of sheets in such a way that the thus admitted sheets invariably assume an optimurn position for engagement by the suction-operated transfer device.

An additional object of the invention is to provide a sheet feeding apparatus which can feed sheets of varying s12es.

Another object of the invention is to provide a sheet feeding apparatus which can be readily combined with a conventional developing unit to supply thereto exposed films in a predetermined sequence, at desired intervals,

3,396,964 Patented Aug. 13, 1968 and in such a way that each of a series of successive films is delivered in the same position.

Briefly stated, one feature of our invention resides in the provision of an apparatus for feeding sheets, particularly for feeding exposed films to a developing unit, which comprises a preferably inclined snpport for the lower edges of a pile of stacked sheets, abutrnent means for engaging the exposed surface of the foremost sheet of the pile on the support and for thereby maintaining the sheets of the pile in a position of preferably slight inclination with reference to a vertical plane, stop means extending upwardly from the Support to abut against the exposed surface of the foremost sheet in the region of the lower edge of such sheet, suction-operated transfer ineans including one or more suction cups disposed in freut of the foremost sheet, operating means f0r moving the transfer means up and down whereby the transfer means respectively lifts the foremost sheet over the stop means and thereupon shifts the thus lifted sheet downwardly in front of the stop means, and advancing means for moving the thus shifted sheet along a predetermined path, for exan1ple, past a series of developing, fixing, washing, drying and other stations in a film developing unit.

Due to the fact that the sheets of the pile which rests on the aforernentioned support are slightly inclined With reference to a vertical plane, the sheets remain properly stacked but the pressure upon the foremost sheet which is in actual contact with the abutment means is not excessive so that the suction-operated transfer means can readily carry the foremost sheet over the stop means and into the range of advancing means. Such advancing means may comprise pairs of driven rolls or analogous advancing members which can be arrested by a detector assembly positioned to scan the sheets which are withdrawn from the pile in order to detect sheets of excessive thickness or packages of two er more sheets which might adhere t0 each other.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended clairns. The improved sheet feeding apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of a specific embodiment with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a film developing machine comprising a sheet feeding apparatus which embodies the present invention;

FIG. 2 is an enlarged schematic vertical section through the apparatus substantially as Seen in the direction of arrows from the line IIII of FIG. 1; and

FIG. 3 illustrates the electric circuit of the sheet feeding apparatus.

Referring -to FIG. 1, the developing machine comprises a developing unit 1 of known construction and a novel apparatus 2 which feeds sheets of exposed film to the developing unit. The latter includes developing, fixing, washing and drying stations and a conveying system which advances sheets of film past such stations and tovvard a discharge opening at the remote side of the machine. The housing cf the developing unit 1 is sealed against entry of light raus so that it can be installed in a lighted area. However, the sheet feeding apparatus 2 must receive sheets in a dark room and is separated from the unit 1 by a partition 57 constituting one wall of a dark room. In FIG. 1, the dark room is at the front side of the par-tition 57, and the latter is provided with an opening, shown in FIG. 2, for introduction of successive sheets into the developing unit 1.

The front Wall 1a of the developing unit 1 carries a platform 1b for the sheet feeding apparatus 2 which is assembled independently of the unit 1 and is preferably detachable frorn the platform 1b. The apparatus 2 rei sembles a leetern or console and includes a substantially horizontal control panel 2a disposed close to the platform 1b and provided with signal lights, push buttons and other control elements which will be described later. The upper portion of the apparatus 2 comprises an outer wall 2b which consists of opaque material. A hinged cover or lid 2c is disposed between the control panel 2a and a horizontal slit-shaped auxiliary sheet-admitting opening 2d. A manually operable sheet transporting wheel 3 is mounted n a side Wall of the apparatus 2 and serves to advance groups of two 0r more sheets through the evacuating opening which is normally concealed by the lid 2c.

The supply device which delivers fresh supplies of stacked sheets into the interior of the sheet feeding apparatus 2 is located in front of the developing unit 1 and includes a holder o1 guide 4 for a horizontally reciprocable pusher 5. The latter is dimensioned to introduce stacks 01 larger or smaller sheets and resembles a frame provided with a sheet-engaging front face Sa. A handle 5b may be gripped by band to move the pusher 5 t0 and from the retracted position shown in FIG. 1.

A fresh supply 0f sheets 100 is indicated in FIG. 1 by phantom lines. The foremost sheet abuts against the horizontal bars 4a of the guide 4 and the right-hand vertical edges of all of the sheets 100 are located in the pathway of the front face 5a. When the Operator moves the handle 5b in a direction to the left, the front faee 5a transfers the sheets into the interior of the sheet feeding apparatus 2 wherein the rearrnost sheet 100 comes into the range of one or more elastic presser members 105 (see FIG. 2) which move the sheets in a direction toward the artition 57 and away from alignrnent with the front face 5a. The position of presser members 105 in the apparatus 2 is such that they can move piles consisting of small, large or medium-sized sheets. The rightband vertical edges of sheets 100 rernain in a comrnon plane because, during transfer into the interior 015 the apparatus Z, such vertical edges abut against the front face 5a. This is important because the suction-operated transfer device 9 of the sheet feeding apparatus 2 (see FIG. 2) is positioned to properly engage and transfer sheets whose right-hand vertical edges are located in a comrnon plane.

The housing of the sheet feeding appaartus 2 has a narrow right-hand vertical wall, a portion of which constitutes an elongated gate 58 turnable on hinges 58a and normally sealing the internal space of the apparatus. The pusher 5 has an opening member in the form of a rod 01' bar 5d which opens the gate 58 when the operator moves the handle 5b from the retracted position of FIG. 1. The gate 58 insures that the interior of the apparatus 2 is normally sealed against entry of light and that the pile 0f sheets in the apparatus is not damaged even if light is allowed to penetrate into the dark room.

FIG. 2 illusrates the details of the sheet feeding apparatus 2. Two parallel inner Walls 2e and 2 define between themselves a compartrnent 101 and makewith a vertical plane an angle 0f lass than 45 degrees, preferably about degrees. The compartment 101 serves to accornn1odate a pile of stacked sheets 100 received through the main opening which is normally sealed by the gate 58, and the lower horizontal edges of such sheets rest on an inclined support 7. An abutment 6 on the front inner Wall 21 extends into the compartment 101 and is engaged by the exposed front surface of the foremost sheet 100a. This abutment is subjected to a certain pressure because the sheets of the pile in the compartment 101 are inclined with reference 10 a truly vertical plane. The inclination is slight so that the abutrnent 6 4 does not offer excessive resistance to sliding movement of the forernost sheet 100a.

The support 7 makes with a horizontal plane an angle of substantially 30 degrees and is inclined downwardly toward the front inner Wall 21. The lowermost portion 0f the support 7 carries an upwardly extending stop or obstruction 8 which abuts against the front surface of the foremost sheet 100a in the region 0f the lower horizontal edge 0f this sheet. The stop 8 is inclined and Inakes with a truly vertical plane an angle in excess of 10 degrees, i.e. it is inclined with reference to the inner walls 2a and 2f. The distance between the rear inner Wall 2e and stop 8 corresponds to maximum thickness 0f a pile in the compartrnent 101. The front inner wall 21 and stop 8 define between themselves a gap 102 whose Width preferably approxirnates one-fifth of the distance between the rear inner Wall 2e and stop 8 The front inner Wall 2f has an elongated slot for the aforernentioned suction-operated transfer member 9 (hereinafter called suction cup for short), The construction of operating means for the suction cup 9 is preferably of the type as known from the art of motion picture apparatus. Such operating means includes a system of cams which impart to the suction cup 9 a movement along a closed polygonal path indicated in FIG. 2 by hantom lines 103. The cup 9 normally assumes its lower end posi tion and, when starting to perforrn a working cycle, moves upwardly to the solid-line position of FIG. 2, thereupon downwardly to a median position, forwardly toward the adjoining exposed surface of the foremost sheet 100a to pneumatically attract the sheet, thereupon away from the rear inner Wall 2c, upwardly to the position shown in FIG. 2 downwardly toward the gap 102, and again in a direetion away from the Wall 2e. This cup will attract the sheet 100a during first movement away from the Wall 2e, during ensuing upward movement, and finally during downward movement toward the gap 102. The sheet is released when the cup reaches its lower end position and covers a short distance in a direction away frorn the Wall 2e. During such second travel of the cup away from the Wall 2e the suction is terminated so that the sheet 100a can descend in the gap 102 by gravity. The

lower edge of the sheet 100a will hurdle the stop 8 in response to upward and subsequent downward movement of the cup 9. The manner in which suitable valves (not shown) control' the connection between the cup 9 and a suetion pump or other source of negative pressure 1s well known frorn the art 0f printing machinery and is not shown in the drawings.

The aforementioned operating means for the suction cup 9 further cornprises a prime mover here shown as an electric motor 10 which drives a step-down transmission having an output shaft 11. One full revolution of the shaft 11 suffices to move the suction cup 9 from its starting position, along the closed path 103 and back to starting position, i.e. to effect transfer 0f the foremost sheet a from the compartment 101, over the stop 8 and into the gap 102. The output shaft 11 also operates a microswitch 12 which automatically arrests the motor 10 when the shaft 11 completes a full revolution.

The output shaft 11 drives a link train 13 serving to transmit motion to an intercepting member 14 which is reciprocable below the front inner Wall 2 and across the gap 102. The intercepting member 14 is located at a level below a first pair of constantly driven advancing rolls 15, .16 which are movable toward and away from each other, i.e., into and away from motion transmitting engagement with a sheet 100a in the gap 102. The arrangement is such t'r1at the rolls 15, 16 move toawrd each other t0 close the gap 102, when the intercepting member 14 is withdrawn from the gap, and vice versa. The rolls 15, 16 derive reciprocatory motion from the output shaft 11 but the means l'or rotating these rolls preferably forms part o1 the aforementioned conveying system in the developing unit l. This insures that the rolls 15, 16 are driven in synchronism with the remaining sheet-advancing or conveying elements.

Two detectors or sensor rolls 17, 18 are installed at a level below the intercepting member 14 and respectively serve as trips for microswitches 19 and 20. The sensitivity of the microswitch 19 is selected in such a way that it closes When the nip between the detector rolls 17, 18 accornmodates a sheet of average thickness; the microswitch 20 will close When the nip between the detector rolls 17, 18 accommodates a sheet of excessive thickness or a package of two or more sheets of normal thickness. The rolls 17, 18 are idler rolls, i.e., they do not contribute to forward movement of sheets into the developing unit .1. The diflerence in sensitivity or setting of microswitches 19, 20 is such that the microswitch 20 will close in response to detection of material having a thickness exceeding a permissible thickness by the thickness of a normal sheet.

The sheet feeding apparatus 2 further cornprises a rockable deflector in the form of a flap 21 mounted below the detector roll 17 and turnable about a fixed horizontal axis. The flap 21 is rockable by an electromagnet 22 and is movable to a position in which it prevents travel of successive sheets along a predetermined path defined by the advancing rolls 15, 16 and by additional pairs of driven advancing rolls 23, 24, 25, 26, 27 and 28. These rolls normally advance successive sheets into the developing unit 1. When the flap 21 is caused to move across such path, a sheet advanced by the rolls 15, 16 will be diverted in a direction to the left, as viewed in FIG. 2, to travel along a bottom wall 2g and to issue from the apparatus through the opening which is normally sealed by the hinged lid 2c. The gears which can be driven by the aforementioned transporting wheel 3 to bring about movement of sheets along the bottom wall 2g are indicated in FIG. 2 by hantom lines.

Closing of the microswitch 20 takes plade simul taneously with deenergization of an electromagnetic clutch 29 which is installed in the drive for the advancing rolls 15-16, 23-28 so that the conveying system is arrested when the rolls 17, .18 detect a package of two or more sheets or a single sheet of excessive thickness. In addition, the microswitch 20 then energizes the electromagnet 22 so that the flap 21 automatically diverts the package onto the bottom wall 2g. Adherence of sheets to each other will be cause.d by moisture or by static electricity. Simultaneous entry of. two or more sheets could cause disturbances in functioning of the developing unit 1 and would invariably result in damage to all or all but one sheet of a package.

The path defined by the advancing rolls 23-28 is substantially horizontal. In front of this path (ie., to the left as viewed in FIG. 2) there are provided additional advancing rolls 30, 31 which can advance successive sheets into the nip between the rolls 23, 24, When such sheets are fed through the auxiliary opening 2d. The additional rolls 30, 31 receive motion from the drive for the rolls 15, 16, 23-28 throug-h a suitable claw clutch which is not shown in the drawings. A blocking flap 32 is located downstream of the rolls 30, 31 and is rockable by an electromagnet 33. This electrornagnet also controls the aforementioned claw clutch which drives the rolls 30, 31. These rolls will rotate in response to energization of the elect-romagnet 33. A detector or sensor lever 34 is adjacent to the blocking flap 32 to close a microswitch 35 when a sheet passes over the flap 32.

The outer wall 2b has an opening for the detectors or trips 36 of two mic- roswitches 37, 38 which are installed in the circuit of three signal lamps on the control panel 2a. These signal lamps Will indicate whether the compartment 101 is empty, nearly filled or halfway filled so that the operator Will know when to introduce a fresh supply of sheets by means of the pusher 5.

FIG. 3 shows the electric circuit of the sheet feeding apparatus. Two power leads 39, 40 are connected with a source of A-C current. The first brauch between these power leads includes a master switch 41, a starter switch 42 and a relay 43 connected in series with the switches 41, 42 and having working contacts 43a, 43b, 43c. The contact 43a is connected in parallel with the starter switch 42 and insu=res that the relay 43 remains energized even if the switch 42 is opened immediately after closing. A signal lamp 44 which is connected in series with contact 43a lights up When the relay 43 is energized to indicate that the sheet feeding apparatus 2 is in operation.

The second working contact 43b is connected in series with a two-way switch 45a which is controlled by a sec ond relay 45, the latter =being energizable in response to closing of the microswitch 20. When the relay 45 is energized, the two-way switch 45a completes the circuit of a warning lamp 46.

Two additional relays 47, 48 are connected in parallel with each other and in series With the microswitches 19, 35. The relay 48 is connected in parallel Wtih a signal lamp 49. The microswitch 12 is a two-way switch. When held in the position of rest, the microswitch 12 is connected in series with the first contacts 47a, 48a of the relays 47, 48 and with a time-delay relay 50. When moved to its second position, the microswitch 12 completes the circuit of the electric motor 10. This microswitch 12 is connected in parallel with the second contacts 47b, 48b of the relays 47, 48.

A further branc-h of the circuit shown in FIG. 3 contains the working contact 430 of the relay 43 in series with the prima=ry winding of a transformer 51 and with microswitches 37, 38. These microswitches are respectively connected in series with signal lamps 52, 53 and 54. The signal lamps 52-54 are installed on the control panel 2a and indicate the height of the pile on the compartment 101.

The secondary winding of the transformer 51 is connected with a rectifier 55 whose output is connected with the working contact 50a of the time-delay relay 50, the latter being in series With the electromagnet 33. The microswitch 20 is connected in parallel With the working contact 50a and electromagnet 33 and in series With the relay 45. This microswitch 20 can 'be bypassed by a concluctor containing a working contact 45b of the relay 45 in series with an inter-rupter switch 56 which is coupled With the starter switch 42. A further contact 45c of the relay 45 constitutes a two-way switch and can complete the circuit of the electromagnet 22 01' electromagnetic clutch 29. The clutch 29 isenergized When the relay 45 is deenergized and the switch 45c assumes the position shown in FIG. 3.

The Operation is 'as follows:

The pusher 5 can introduce into the compartment 101 a desired number of sheets 100. The length of strokes of this pusher is always the same so that the right-hand edges of all sheets in the compartment 101 Will be located in a predetermined plane and the foremost sheet a is ready to be transferred by the suction cup 9. The sheets of the pile in the compartment 101 rest on the inclined support 7. The operator knows the maximum and minimum sizes of sheets which can be fed into the apparatus 2 to be properly transferred by the cup 9 and to be thereupon ad vanced by the rolls 15, 16. The lower trough-shaped momber 4b of the guide 4 supports the lower edges of sheets 100 which are located in the path of the front face 5a on the pusher 5. The pusher 5 has claws 5c which extend into the slots between the bars 4a of the guide 4 and insure that all sheets of the pile are properly advanced toward the gate 58 and into the compartment 101. The claws 5c also prevent the sheets from slipping between the pusher 5 and bars 4a.

The compartrnent may accornmodate a desired number of sheets, for example, a pile of sixty stacked sheets.

Since the pile on the Support 7 leans against the abutment 6, the foremost sheet 100a is always located in an optirnum position for engagement by the suction cup 9,

even if the pile is reduced t a Single sheet. By being compelled to move up and thereupon -down and into the gap 102, the foremost sheet 100a is more likely to be separated from the next-following sheet.

When the microswitch 19 is open because there is no sheet between the detecto-r rolls 17, 18, and When the microswitch 35 is open because the lever 34 has detected no sheets above the flap 32, the contacts 47b, 48b of the relays 47, 48 are closed. The motor 10 will be started in response to closing of master switch 41 and startet switch 42 because the latter energizes the relay 43 whose working contact 43b completes the circuit of the motor. Shortly after the motor 10 begins to run, the output shaft 11 changes the position of the microswitch 12 through a cam 11a shown in FIG. 3 whereby the microswitch 12 changes its positiom and completes the circuit of the motorl0 independently of the contacts 47b, 48b. The shaft 11 causes the suction cup 9 to transfer the foremost sheet 100a into the gap 102. Such sheet will be disengaged from the suction cup when the latter assumes its lowerrnost position and moves away from the stop 8 because such movement of the suction cup causes the a-forementioned valves to disconnect the cup from the source of negative pressure and to admit atmospheric air into the evacuated space within the cup.

When a freshly transferred sheet 100a is released =by the suction cup 9, such sheet descends onto the intercepting member 14 so that it is properly oriented with reference to the advancing rolls 15, 16 which -are held in their retracted positions shown by solid lines. The intercepting member 14 insures that the lower edge of each successive sheet 100a is maintained in a predetermined position before the sheet is actually engaged by the rolls 15, 16. Since the inclination of the inner Walls 2e, 2 is relatively small, the pressure exerted by a pile cf maximum thickness against the foremost sheet 100a which is in contact with the abutment 6 is still relatively small so that the cup 9 can readily transfer such sheet into the gap 102. As the output shaft 11 continues to rotate, the link train 13 retracts the intercepting member 14 and the advanoing rolls 15, 16 a-re caused to move toward each other (to assume the phantom-line positions shown in FIG. 2)

whereby the sheet 100a is engaged from opposite sides and along its full width and is fed on toward the rolls 23, 24. During such travel, the sheet advances between the detector rolls 17, 18 and along suita=ble guides provided in the housing of the apparatus 2. Once it is engaged by the rolls 23, 24, the sheet 10022 continues to travel in the a1f0remntioned horizontal path between the rolls 25, 26 and 27, 28 and into the interior of the developing unit l. Certain components of the gear train which comnects the advancing rolls 15, 16 and 2328 for rotation at the same speed are indicated in FIG. 2 by phantornline circles.

When the trailing (upper) edge of the sheet 100a moves downwardly and beyond the = detectors 17, 18, the rncroswitch 19 opens automatically and the relay 47 is deenergized to close its contact 47b.

The next following cycle begins as soon as the startet switch 42 is closed again or if the starter switch remains closed. The interval which elapses between the passage of a preceding sheet beyond the detector rolls 17, 18 and the entry of the next-following sheet insures that the successively delivered sheets cannot interfere with each other.

If the suction cup 9 happens to transfer two or more sheets at a time (for example, because such sheets adhere to each other due to electrostatic charging), the pack of two or more sheets will cause the detector roll 18 to close the microswitch 20 which energizes the relay 45. This relay remains energized on closing o f its working contact b even if the microswitch 20 opens again. Energization of relay 45 will bring about a change in the position of switches 45a and 450 whereby the switch 45a com pletes the circuit ol the warning lamp 46 and simultaneously opens the circuit of motor 10 and relays 47, 48,

50. The switch 45c deenergizes the electromagnetic clutch 29 and energizes the electromagnet 22. The clutch 29 arrests the advancing rolls 15, 16 and 23-28, and the electromagnet 22 changes the position of the flap 21 so that the latter diverts the pack of two 01 more coherent s-heets from their normal path and Ioward the bottom Wall 2g. The expulsion of this pack through the opening which is normally sealed by the lid 2c takes place in response to manual rotation of the transporting wheel 3 which can drive the advancing rolls 15, 16.

When the pack of t-wo or more sheets is withdrawn at the rear side of the apparatus 2, the relay 45 is still energized because its working contact 45b is closed. This relay will -be deenergized in response to closing of the starter switch 42 which is connected with and then opens the interrupter switch 56. The apparatus is now ready to resurne normal operation.

It happens from time to tirne that a ifreshly received sheet of film must be developed out of turn. For example, a freshly taken X-ray picture of a sick person must be developod without delay, i.e., ahead of the film sheets which are accomrnodated in the compartment 101. This can be done by the simple expedient of feeding such freshly received sheet through the -auxiliary opening 2d and into the nip between the advancing rolls 30, 31 which bear against each other with a small pressure and prevent penetration of light into the housing of the apparatus 2. The sheet then comes into abutment with the blocking flap 32 and changes the position of the detector lever 34 which closes the microswitch 35 to energize the relay 48. The contact 48a closes and the contact 48b opens. This means that, as soon as the working cycle which was in progress is completed, the motor 10 cannot be started again and the suction cup 9 remains in its position of rest so that no transfer o1f a fresh sheet from the compartment 101 will take place. As the trailing edge of the last sheet which has 'been transferred by the suction cup 9 moves beyond the detector rolls 17, 18, the microswi'tch 19 opens and the relay 47 is deenergized to close its contact 47a and to open the contact 47b. The motor 10 will come to a halt as soon as the cam 11a completes a full revolution and the microswitch 12 retu:rns to the position shown in FIG. 3. T his energizes the relay 50 with a predetermined delay, for example, with a rlelay of five seconds. Such delay is desirable to insure that the sheet which was introduced through the opening 2d cannot catch up with the last sheet which was transferred by the suction cup 9.

When the relay 50 is energized, it closes the contact 50a to energize the electromagnet 33 which connects the advan-cing rolls 30, 31 with the drive and retracts the blocking flap 32. The freshly received sheet then -advances in response to motion transmitted by the rolls 30, 31 and -its leading edge enters the nip =bet-ween the advancing rolls 23, 24. From thereon, the freshly admitted sheet is treated in the same way as the sheets which are fed by the suction cup 9. The latter remains idle as long as the microswitch 33 remains energized.

The operator can admit one 0r more additional sheets through the opening 2d. If this is not necessary, the sheet feeding a-pparatus will -resume its normal operation.

The structure shown in FIG. 1 is especially suited f0r developing of X-ray pictures. However, it can be used with equal advantage in developing of filrns which are used in graphic arts. The sheet feeding apparatus 2 can be used independently of the developing unit 1 wherever it becomes necessary to separate sheets from a pile in the same sequence in which the sheets are being added to the pile, and wherever one or m0re sheets must be advanced out Of order. This sheet feeding apparatus insures that the sheets are removed from a pile in the compartrnent 101 in the same sequence in which thay are admitted into the apparatus, i.e., that the suction cup or cups 9 will invariably transfer all sheets of a pile which was inlr0duced hy the pusher 5 in a preceding step beforo the cup or cups 9 begin to transfer sheets which were admitted by the pusher in the next-following step. This is often important in processing cf films by insuring that no sheet will dwell in the apparatus for excessive periods of time.

What is claimed as new and desired to be protected by Letters Patent is:

1. Apparatus for feeding sheets, particularly for feeding sheets of exposed film to a developing unit, comprising a support for the lower edges of a pile of stacked sheets; abutment means for the forernost sheet of such pile to maintain the sheets in a position of inclination with reference to a vertical plane; stop means extending upwardly from said support adjacent to the foremost sheet of the pile in the region of the lower edge of such sheet; suction-operated transfer means disposed in front of said foremost sheet; operating means for moving said transfer means first in a direction upwardly parallel to the foremost sheet of said pile of stacked sheets and thereafter in a direction away from said pile of stacked sheets whereby the transfer means first moves said foremost sheet of the pile along the pile out of engagement with said stop means and thereupon away from said pile, locating it on said support in front of said stop means; and advancing means for moving the thus located sheet along a predetermined path.

2. Apparatus as set forth in claim 1, wherein said ahntment means is arranged to maintain the sheets of said pile in a position of inclination in which the sheets make With a vertical plane an angle of less than 45 degrees.

3. Apparatus as set forth in claim 1, wherein said support has a top surface which is inclined downwardly in a direction toward said stop means.

4. Apparatus as set forth in claim 1, wherein said advancing means comprises at least one pair of cooperating driven advancing rolls.

5. Apparatus as set forth in claim l, wherein said advancing means comprises a pair of advancing members located at the opposite sides of the sheet which is located in freut of said stop means t advance such sheet along said predeterrnined path, and further comprising detector means adjacent to said path for scanning the sheets which are advanced by said members and arranged to produce signals in response to detection of excessive thickness of the material passing between said advancing members.

6. Apparatus as set forth in claim 5, wherein said detector means comprises at least one normally open switch and trip means for closing said switch in response to detection of excessive thickness of material passing between said advancing members.

7. Apparatus as set forth in claim 5, further comprising deflector means movable across said predetermined path downstream of said advancing members and means for moving said deflector means across said path in response to detection of excessive material thickness by said detector means whereby the deflector means diverts such material from said path.

8. Apparatus as set forth in claim 7, wherein the means for moving said deflector means comprises an electromagnet and said detector means comprises switch means and means for closing said switch means in response t0 detection of excessive material thiekness whereby said switch means energizes said electromagnet to eflect movement of said deflector means across said path.

9. Apparatus as set forth in claim 7, further comprising manually operated transporting means for materiell which is diverted by said deflector means.

10. Apparatus as set forth in claim 1, wherein said transfer means comprises a suction cup movable along a closed path including a lowermost portion in which the cup travels in a direction away from said stop means, a source of negative pressure normally connected with said cup and valve means for disconnecting the cup from said source of negative pressure in response to travel 0f said cup in the lowermost portion of said closed path.

11. Apparatus as set forth in claim 10, wherein said transfer means further comprises means for admitting into said cup air at atmospheric pressure in response to travel of the cup along the lowermost portion of said closed path.

12. Apparatus for feeding sheets, particularly for feeding sheets of exposed filrn to a developing unit, comprising a support for the lower edges of a pile of stacked sheets; abutment means for the forernost sheet of such pile to maintain the sheets in a position of inclination with reference to a vertical plane; stop means extending upwardly from said support adjacent to the foremost sheet of the pile in the region of the lower edge of such sheet; suction-operated transfer means disposed in front of said foremost sheet; operating means for moving said transfer means up and down whereby the transfer means locates the foremost sheet of the pile on said support in front of said stop means; advancing means for moving the thus located sheet along a predetermined path; and supply means for delivering fresh supplies of sheets onto said support, comprising holder means arranged to carry a fresh supply of sheets in substantial parallelism with the sheets of the pile on said support, and reciprocable pusher means for displacing such supply of sheets from said holder means to a position behind the sheets of the pile on said support.

13. Apparatus as set forth in claim 12, further comprising presser means for moving a supply of sheets located behind said pile in a direction toward the rearmost sheet of the pile and away from registry with the pusher means.

14. Apparatus as set forth in claim 13, wherein said presser means comprises at least one resilient presser member.

15. Apparatus as set forth in claim 12, further comprising a housing accommodating said support and all of said means and defining a compartment located above said support, said housing having a sheet-admitting opening disposed between said pusher means and said compartment and a gate movable between an open position and a normal closed position in which said opening is sealed, said pusher being movable from a retracted position in which a fresh supply of sheets can be placed onto said holder means to a second position to thereby move such fresh supply of sheets through said opening and into said compartment, and further comprising motion transmitting means responsive to movernent of said pusher means from retracted position to move said gate means to open position.

16. Apparatus as set forth in claim 15, wherein said gate means is hingedly secured to said housing and said motion transrnitting means is fixed to said pusher means.

17. Apparatus for feeding sheets, particularly for feeding sheets of exposed film to a developing unit, comprising a support for the lower edges of a pile of stacked sheets; abutment means for the foremost sheet of such pile to maintain the sheets in a position of inclination With reference to a vertical plane; stop means extending upwardly from said support adjacent to the foremost sheet of the pile in the region of the lower edge of such sheet; suction-operated transfer means disposed in freut of said foremost sheet; operating means for moving said transfer means up and down whereby the transfer means locates the forernost sheet of the pile on said support in front of said stop means, comprising electric motor means, rotary =shaft means driven by said motor means and arranged t-o transrnit motion to said transfer means, and means for arresting said motor means in response to a full revolution of said shaft means; and advancing means for moving the thus located sheet along a predetermined path.

18. Apparatus as set forth in claim 17, further comprising starter means for completing the circuit of said motor means.

19. Apparatus as set forth in claim 17, wherein said arresting means comprises switch means connected in the circuit of said motor means and cam means driven by said shaft rneans to open saidswitch means on completion of a full revolution by said shaft means.

20. Apparatus for feeding shcets, particularly for feeding sheets of exposed filrn to a developing unit, comprising a support for the lower edges of a pile of stacked sheets; ahutrnent means for the foremost sheet f such pile to rnaintain the sheets in a position of inclination with reference to a vertical plane; stop means exterrding upwardly from said support adjacent to the forernost sheet of the pile in the region of the lower edge of such sheet; suction-operated transfer rneans disposed in front of said foremost sheet; operating means for moving said transfer means up and down whereby the transfer means locates the fo-rernost sheet of the pile on said support in front of said stop rneans, said transfer means being arranged to automatically release said foremost sheet subsequent to placing cf such sheet in front of said stop means so that the sheet is than free to descend by gravity; advancing means for moving the thus located sheet along a predetermined path; and intercepting means movable into the path of the descending sheet to temporarily support the lower edge of such sheet whereby the latter is orientcd prior to engagement by said advancing rncans.

21. Apparatus as set forth in claim 20, wherein said advancing rneans co-mprises a pair of driven rolls .located at a level below said intercepting rneans and disposed at the opposite sides of a sheet.whose lower edge is supported by said intercepting means, said rolls being movable toward and away frorn each other, and further comprising means for moving said rolls toward each other when said intercepting means is moved from the path of said descending sheet, and vice Versa.

22. Apparatus for feeding sheets, particularly for feeding sheets of exposed film to a developing unit, comprising a support for the lower edges of a pile of stacked sheets; abutment rneans for the foremost sheet 0f such pile to maintain the sheets in a position of inclination with reference to a vertical plane; stop means extending upwardly frorn said support adjacent to the foremost sheet of the pile in the region of the lower edge of such sheet; suction-operated transfer means disposed in front of said foremost sheet; operating means for moving said transfer rneans up and down whereby the transfer means locates the foremost sheet of the pile on said support in front of said stop rneans; advancing means for rnoving the thus located sheet along a predetermined path, comprising a pair 0f advancing mernbers located at the opposite sides of the sheet which is located in freut of said stop means to advance such sheet along said predetermined path; and detector means adjacent to said path for scanning the sheets which are advanced by said advancing members and arranged to produce signals in response to detection of: excessive thickness of the material passing between said advancing members, comprising two normally open switches and a pair of trips one of which is arranged to close one of said switches in response to detection of a first material thickness and the other of which is arranged to close the other switch in response to detection of a greater second material thickness, the difference between said first and second thicknesses approxirnating the average thickness of a sheet.

23. Apparatus as set forth in claim 22, further comprising a drive for said advancing means including clutch means arranged to be disengaged in response to closing of said other switch means to thereby arrest said advancing rnembers.

24. Apparatus for feeding sheets, particularly for feeding sheets of exposed film to a developing unit, comprising a support for the lower edges of a pile of stacked sheets; abutment means for the foremost sheet of such pile to maintain the shcets in a position of inclination with reference to a vertical plane; stop means extending upwardly from said support adjacent to the foremost sheet of the pile in the region of the lower edge of such sheet; suction-operated transfer means disposed in front o-f said forernost sheet; operating means for rnoving said transfer rneans up and down whereby the transfer means locates the forernost sheet of the pile on said support in front of said stop means; advancing means for moving the thus located sheet along a predeterrnined path; and additional advancing means for feeding sheets supplied from a source other than said pile into said predeterrnined path.

25. Apparatus as set forth in claim 24, further comprising a housing providing an airtight enclosure for said support and all of said rneans, said housing having an auxiliary sheet admitting opening for supplying sheets to said additional advancing means.

26. Apparatus as set forth in claim 25, wherein said additional advancing means cornprises a pair of rotary advancing rolls which prevent entry of light through said auxiliary opening.

27. Apparatns as set forth in claim 24, further compriz;ing detector rneans arranged to detect the sheets fed by said additional advancing means.

28. Apparatus as set forth in claim 27, Wherein said dete :tor means co-mprises switch means and trip means for closing said switch means in response to detection of sheets fed by said additional advancing rneans, and rncans for inactivating said operating mcans in rcsponse 10 closing of said switch means.

29. Apparatus for feeding sheets, particularly for feeding sheets of exposed filrn to a developing unit, comprising a support for the lower edges of a pile of stacked sheets, abutrnent rneans for the foremost sheet of such pile to maintain the sheets in a position of inclination with reference to a vertical plane; stop means extending upwardly from said support adjacent to the forernost sheet 0f the pile in the region cf the lower edge of such sheet; suction-operated transfer means disposed in front of said foremost sheet; operating means for moving said transfer means up and down whereby the transfer means locates the foremost sheet of the pile on said support in front cf said stop means, comprising electric motor means, shaft means driven by said motor means and arranged to mo-ve said transfer rneans, and switch means connected in series With said motor means and arranged to arrest said motor means in response to a full revolution of said shaft means; advancing means for moving the thus located sheet along a predetermined path; a first relay having a contact connected in parallel with said switch means and in series with said motor means; a second relay having a contact connected in series with said first mentioncd contact; first detector rneans for scanning the thickness of material which is being advanced along said path by said advancing means and for energizing said first relay in response to detection of satisfactory material thickness to thereby open said first mentioned contact; additional advancing means for admitting into said predeterrnined path sheets from a source other than the pile on said support; and second detector means for scanning the sheets fed by said additional advancing means and arranged to energize said second relay in response to detection of a sheet whereby said seconcl relay opens the respective contact, said switch means heilig movahle between two positions in 0ne of which it connects said motor means With a source of electrical energy independently of said contacts and in the other of which the motor means can be connected with the source of electrical energy only through said contacts.

30. Apparatus as set forth in claim 29, Wherein said relays comprise second contacts in series with said switch means in the other position thereof, and further comprising a tirne-delay relay connected in series with said second contacts and arranged to start said additional advancing means with a predetermined delay following inactivation 0f said motor means in response to completion of a full revolution of said shaft mezms und 011 energization of said second relay- 31. Apparatus as set forth in claim 30, further comprising blocking means normally extending across the path of sheets fed by said additional advancing means and means for withdrawing said blocking means in response to energization of said time-delay relay.

32. Apparatus as set forth in claim 30, wherein said tirne-delay relay is connected in parallel with said motor means, and further comprising a fourth relay having a contact normally connected in series with said motor means and said time-delay relay, said last-mentioned contact being moved to a second position 011 energization of said fourth relay in response to detection of excessive material thickness by said first detector means.

33. Apparatus as set forth in claim 32, wherein said first detector means comprises a microswitch connected in series with said fourth relay and trip means for closing said microswitch in response to detection 0f excessive material thickness.

34. Apparatus as Set forth in claim 33, wherein said fourth relay comprises a second contact connected in parallel with said microswitch and further comprising a Starter switch for said motor means and an interrupter switch connected in series With the second contact 01 said fourth relay and arranged to open in response t0 closing 0f said starter switch.

References Cited UNITED STATES PATENTS 2129230 9/1938 ONeil 271-57 X 1,204188 11/1916 Pye 27111 2915308 12/1959 Matzen 2715 3008385 11/1961 Pierce 27126 X 3339918 8/1967 Gote 209-7 X EDWARD A. SROKA, Primary Examz'ner.

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